This invention relates in general to setting antifriction bearings and more particularly to a gauging apparatus and process for setting such bearings.
A shaft which rotates within a housing requires bearings of some type to support it in the housing, and where the shaft must rotate with precision or carry significant radial and axial loads, the bearings are often single row tapered roller bearings. When mounted in pairs, these bearings must be adjusted against each other to control the end play or preload in the bearings, or in other words, to bring the bearing to the proper setting. Too much end play detracts from the stability of the shaft. Preload, while keeping the shaft rotating about a fixed axis, if excessive, will produce too much friction within the bearings and cause them to experience early failure.
Within a pair of single row tapered roller bearings the setting depends on the axial spacing between the inner races or cones of the two bearings and the axial spacing between the outer races or cups of the two bearings. Various procedures and appliances exist for determining the proper spacing. Changing the spacing between either the cones or the cups will alter the setting for the combination.
Tapered roller bearings find widespread use in automotive equipment--from small automobiles to large trucks. In the typical rear wheel drive vehicle, the longitudinal drive or propeller shaft is connected to a pinion shaft which forms part of the vehicle's differential. That shaft rotates on two single row tapered roller bearings which are located in a housing. The shaft must rotate with considerable precision, lest the pinion carried by it will not mesh properly with the large ring gear in the differential and thereby produce noise and excessive wear. To achieve this precision, the shaft and housing must not only be machined accurately, but the bearings must be set properly to a condition of slight preload where no radial or end play exists in the pinion shaft.
Several procedures exist for setting these bearings. One of the more popular for setting the pinion shaft bearings of automotive axles controls the setting of the bearings with a spacer located between the inner races or cones. Typically, the cones are clamped between the pinion and a drive flange, which is in turn secured by a nut, with the spacer determining the distance between the two cones and hence the setting of the bearings.
But selecting the length of the spacer for a long time remained a formidable and time-consuming task, since it in essence relied on a trial and error procedure. With each new spacer, the pinion shaft would be rotated to determine the amount of torque transmitted by the bearings, and when the torque fell within an acceptable range, one assumed that the assembly contained a spacer of proper length.
A procedure developed by The Timken Company eliminates the trial and error procedure by measuring the spacing between the cones, notwithstanding their inaccessibility within the housing. In effect, the space separating the opposing faces of the cones is projected out of the housing where it can be measured. This procedure, however, utilizes a gauge which is dedicated to only bearings of a single type or series in that the gauge has surfaces which match the taper of the raceways for the bearings of only that series. Thus, where an axle assembly line carries axles having bearings of more than one series, only the axles having bearings to which the gauge is dedicated can have their bearings adjusted with the improved procedure. More traditional and time consuming procedures must be used for the remaining axles or else additional gauges must exist along the line for those remaining axles.
The present invention resides in a gauging apparatus which in effect projects surfaces of antifriction bearings out of a housing in which such bearings are located so that distances between critical surfaces may be measured remote from the housing. The apparatus has the capacity to accommodate two different types or series of bearings without undergoing modifications. This invention also resides in a process embodied in the apparatus.